/*!	 context.h
**	 Iterator for the layers behind the current Layer.
**
**	Copyright (c) 2002-2005 Robert B. Quattlebaum Jr., Adrian Bentley
**	Copyright (c) 2012-2013 Carlos López
**
**	This package is free software; you can redistribute it and/or
**	modify it under the terms of the GNU General Public License as
**	published by the Free Software Foundation; either version 2 of
**	the License, or (at your option) any later version.
**
**	This package is distributed in the hope that it will be useful,
**	but WITHOUT ANY WARRANTY; without even the implied warranty of
**	MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
**	General Public License for more details.
**
*/

#ifndef __SYNFIG_CONTEXT_H
#define __SYNFIG_CONTEXT_H

#include "canvas.h"
#include "rect.h"
#include "renddesc.h"
#include "surface.h"
#include "rendering/task.h"

#include <synfig/layers/layer_composite.h>

namespace synfig
{

class Vector;
typedef Vector Point;
class Color;
class Surface;
class CairoSurface;
class RendDesc;
class ProgressCallback;
class Layer;
class Time;
class Rect;

/*!	\class IndependentContext
**	 IndependentContext is a class to warp the iterator for a double queue of layers
* (that is the CanvasBase).
**	\see Layer, Canvas, CanvasBase, Context */
class IndependentContext: public CanvasBase::const_iterator
{
public:
    IndependentContext() { }

    // Constructor based on other CanvasBase iterator
    IndependentContext(const CanvasBase::const_iterator &x): CanvasBase::const_iterator(x) { }

    // Assignation operator
    IndependentContext operator=(const CanvasBase::const_iterator &x)
    {
        return CanvasBase::const_iterator::operator=(x);
    }

    // Sets the context to the Time \time. It is done recursively.
    void set_time(Time time, bool force = false) const;

    // Sets the context outline grow to \outline_grow. It is done recursively.
    void set_outline_grow(Real outline_grow) const;
};

/*!	\class ContextParams
**	 ContextParams is a class to store rendering parameters significant for Context.
**	\see Context */
class ContextParams
{
public:
    // When \c true layers with exclude_from_rendering flag should be rendered
    bool render_excluded_contexts;
    // When \c true layers are visible only in Z_Depth range
    bool z_range;
    // Defines the starting position to apply Z_Depth visibility
    Real z_range_position;
    // Defines the depth of the range of the Z_Depth visibility
    Real z_range_depth;
    // Layers with z_Depth inside transition are partially visibile
    Real z_range_blur;

    explicit ContextParams(bool render_excluded_contexts = false):
        render_excluded_contexts(render_excluded_contexts),
        z_range(false),
        z_range_position(0.0),
        z_range_depth(0.0),
        z_range_blur(0.0) { }
};

/*!	\class Context
**	 Context is a class to warp the iterator for a double queue of layers
* (that is the CanvasBase) with additional information about rendering parameters.
**	\see Layer, Canvas, CanvasBase, IndependentContext, ContextParams */
class Context : public IndependentContext
{
private:
    // Rendering parameters significant for Context.
    ContextParams params;

public:

    Context() { }

    // Constructor based on IndependentContext.
    Context(const IndependentContext &x, const ContextParams &params):
        IndependentContext(x), params(params) { }

    // Constructor based on IndependentContext and other Context (to get parameters).
    Context(const IndependentContext &x, const Context &context):
        IndependentContext(x), params(context.params) { }

    // Constructor based on other CanvasBase iterator and other Context (to get parameters).
    Context(const CanvasBase::const_iterator &x, const ContextParams &params):
        IndependentContext(x), params(params) { }

    Context(const CanvasBase::const_iterator &x, const Context &context):
        IndependentContext(x), params(context.params) { }

    // Returns next iterator.
    Context get_next()const
    {
        return Context(*this + 1, params);
    }

    // Returns previous iterator.
    Context get_previous()const
    {
        return Context(*this - 1, params);
    }

    // Get rendering parameters.
    const ContextParams& get_params()const
    {
        return params;
    }

    //	Returns the color of the context at the Point \pos.
    // It is the blended color of the context
    Color get_color(const Point &pos)const;
    CairoColor get_cairocolor(const Point &pos)const;

    //	With a given \quality and a given render description it puts the context
    // blend result into the painting \surface */
    bool accelerated_render(Surface *surface, int quality, const RendDesc &renddesc, ProgressCallback *cb) const;
    bool accelerated_cairorender(cairo_t *cr, int quality, const RendDesc &renddesc, ProgressCallback *cb) const;

    //	Make rendering task
    rendering::Task::Handle build_rendering_task() const;

    // Returns the bounding rectangle of all the context.
    // It is the union of all the layers's bounding rectangle.
    Rect get_full_bounding_rect()const;

    // Returns the first context's layer's handle that intesects the given \point */
    etl::handle<Layer> hit_check(const Point &point)const;

    // Set Render Method. Passes the information of the render method to use to the layers
    void set_render_method(RenderMethod x);

    // Returns \c true if layer is active with this context_params
    static inline bool active(const ContextParams &context_params, const Layer &layer)
    {
        return layer.active()
               && (context_params.render_excluded_contexts
                   || !layer.get_exclude_from_rendering());
    }

    // Returns a value between 1.0 and 0.0 for layer visibility in z_depth range with this context_params
    static inline float z_depth_visibility(const ContextParams &cp, const Layer &layer)
    {
        if (!cp.z_range) {
            return 1.0;
        }

        float z = layer.get_true_z_depth();
        float p = cp.z_range_position;
        float d = cp.z_range_depth;
        float t = cp.z_range_blur;

        // Out of range
        if (z > p + d + t || z < p - t) {
            return 0.0;
        } else

            // Inside right range
            if (z > p + d) {
                return t > 0.0 ? (p + d + t - z) / t : 0.0;
            } else

                // Inside left range
                if (z < p) {
                    return t > 0.0 ? (z - p + t) / t : 0.0;
                } else
                    // Full visible
                {
                    return 1.0;
                }
    }

    // Returns \c true if layer is active in this context
    inline bool active(const Layer &layer)
    {
        return active(params, layer);
    }

    // Returns \c true if layers is visible in z_depth range in this context
    inline float z_depth_visibility(const Layer &layer)
    {
        return z_depth_visibility(params, layer);
    }

    // Returns \c true if layer is active in this context
    inline bool active()const
    {
        return !(operator*()).empty()
               && active(params, *(operator*()));
    }

    // Returns \c true if layer is visible in z_depth range in this context
    inline bool in_z_range()const
    {
        return !(operator*()).empty()
               && z_depth_visibility(params, *(operator*()));
    }

}; // END of class Context

}; // END of namespace synfig

#endif